CARS (coherent anti-Stokes Raman scattering) is a type of nonlinear vibrational spectroscopy. CARS microscopy has been used previously, however scanning is hitherto required in order to perform three-dimensional (3D) imaging. This makes imaging complex, and makes it difficult to apply existing CARS microscopy techniques to imaging fast physical or chemical processes in 3D.
However, CARS has great chemical selectivity, so improved imaging methods using this technique would be extremely valuable for numerous applications. Similarly, other FWM (four wave mixing) imaging methods would be very useful.